There is a conventional thermal printer, which is provided with a thermal head at positions corresponding to one side and the other side of thermal paper having a thermosensitive layer on both sides, so-called double-side thermal paper, and prints both sides of thermal paper by operating both thermal heads, or prints one side of thermal paper by operating one of the thermal heads (e.g., Jpn. PAT. Appln. KOKAI Publication No. 2001-71569).
Double-side thermal paper is more expensive than thermal paper with a thermosensitive layer on only one side, so-called one-side thermal paper. Therefore, one-side printing using double-side thermal paper is undesirable from an economic viewpoint.